Methods and means for renovating corrosion-deteriorated tanks



June 7, 1960 J. J. McGlLLls ErAL 2,939,801

METHODS AND MEANS Foa RENOVATING coRRosIoN-DETERIORATED TANKS Filedsept. 11, 195e 2 Sheets-Sheet l gw/ l IN V EN TOR.

June 7, 1960 J. J. McG|LL|s ErAL 2,939,801

METHODS AND MEANS FOR RENOVATING coRRosIoN-DETERIORATBD TANKS FiledSept. l1. 1956 2 Sheets-Sheet 2 zz jay-ll Patented June `7, 1.960

. videsl amethod'and'nteans whereby a leaky tank not only may bepermanenti s'ealedat the leak or leaks butmay z 939 801 *be conditionedfoifiirther long service' without danger y that new leaks willsiiyelop,it is of considerable im- METHODS AND MEANS FOR RENOVATING 5 pertencethat the mentioned sealing and conditioning may CORROSION'DETERIORATEDTNKS, V be accomplished while thetank continues filled or partial- JohnJ. MoGinis, 1339 Ash si., and iingh n. Mooiiiis, lY flllelW-tll eilfaidfiwitlleusbstantiel less .0f Oil 'duf- 270 Manomet St., both ofBrockton,.Mass. l lngI-Itlleahng and-fentdltlglulgg ptfoless.

ence,"it is among" eo ts o t e invention opro- Flled SePt n 1956 ser'Nnnul l l0 vide amethod of permanently sealing leak-holes in bottom wallportions of lled or filled oil tanksandv the like,whilesimlilt'aneously"insring against annsubsequentfdevelopment-:ofcorrosion-induced leak-holeswithj Ei in a predeterminedband of bottomWallextending from This invention relates to improvements in methods `1pend to Wend of anyp arcu1ar.-tank f n and means for sealing leaks in oilstoragedanksnrthe. Ammer object-f the nvm -o is to provide 'imethodllkegand for Protecnng tank Walls agalnsndslanol'afwnfn of .permanentlysealing leak-holes in oil storage tanks, service. More particularly, theinvention. provides a and th'elke, wljlgimultaep'sly permamly Pfoten.

method and means for Permanently saallng anynnla'znn ing a predetermined"band-of bottom wall of the tank holes that may have developed in lowerwall portions of V20 an oil storage tank, or the like, or forpermanentlypro tecting said lower wall portions againstlicorrosiverdeterioration, the said sealing and protecting being c ective lyaccomplished without need for emptyingthe tank of s. oil, or otherliquid. ,.-igf'j The present application is a continuationimpart otourapplications Serial No. 348,211, lled April .13, 19 53, `a1id Serial No.423,489, tiled April 15, 1954`. 'ent i.t1ed Method and Means forRenovating Corrosion-Deteriorated 1`ank`s; both now abandoned. ',j .1-Oil storage tanks of the conventi nal sheet metal varieties are subjectto deterioration .-in service dueto corrosion resulting from moisturewhich` unavoidablyfge ts into the tanks in relatively small amounts.anderideses on lower wall portions thereof. Moisture "n Arelativi-.lysmall amounts Ordinarily is Present in* nilflllllnlfenlintn vwall ofthe'tank permanently sealing said covered band the Storage tanks andtends t0 settle anflf'isnndenSe-ln ofwall against any deterioratingeffects of moisture which teflefly 0f the tank WallS-Detel'lolfatlnn'f-'Qfjtlle"tank' maybe present within the tank, thecement in the said Walls, dne t0 OOI'I'OSiOn iS a l'elatlvelygslewPlneeS'S 'and K 4covering mixture-providing a permanently stable protecatank may Serve its PnfPOSeS fOl' elglltf-'ten's twelve, '0l' y tivecovering having the property of absorbing and harmmore years, before theravages ef eerreswn ultimately tessiy. consuming moisture from theinterior of the tank.

ing thereon permanently sealing the said band of bottom from the tankand also sealrenovated. Aoil Ystorage. tank,

orf partially'lled tank is distributed as an adhered prond to end ofAadhered protective cover- I i .l titheY likefwhereinfa' rnix-".,vvtureof fibrous` material andcement deposited intoa-iilled.",tectivecovering. overal predetermined band ofbottom produce one ermere leak holes in the' tank walle-` stiu another object of theinvention is to provide a HeretOfPl'e, an Oil tank Wh0Se Walls havedetel'nfated tankrenovatng methodwhereby a corrosion-deteriorated t0 aeondltlOn 1n .Wlllch Oll leaks f1'0lnftl1e tank-tllfnngh oil storagetank, or the like, may be restored for a fura llle 91' holes eaten by01T0Sl0n thlonghjtnn tank Walls 4 'ther -long life of service Withoutneed for emptying the Oldlnalllv would be enndenlned aS nnt 4f0.1'fnl'tlhel eX- tank but with the contents of the tank serving to oat atended Sel'vCe- SOlnetlnleS Snell a leak llaa been'tenlpo' depositedlmixture into covering relation to a predererily Sealed er patehed testep the leakage 'of eil; until terminen band of bottoni wall of thetank, and with the SnCh time aS the Oldl tank might be l'elllaged by'a-new materials of said mixture providing a stable adhered pro- Gne bnf,S0 far aS We'al'e aware n0 -Plflnlfseallnffof 5 tective covering oversaid-band of bottom wall permanent- Patelllng PI'OCedUl'e hascnntenllflatefl lestnl'atlnniqf a ly, sealing the,4 covered band'against any deteriorating leaky tank t0 a COlldltlOn k111 Wlllell ltCnnldf'felldel'fexeffects of moisture which may be present within thetank, tended further Service WlthOnt danger 0f.?, 'ree nll.ene 0f the-said tank contents and said mixture coacting to eect the Old leak$ 0l`development 0f new leak-.Sq- 5 a .sealed plugging of any leak-hole orleak-holes that Leaks in oil storage tanks, due tocorro'sion,d'evelope-` may have been present in the said band of bottom wall ofonly at lower wall portions of the tanks because moisture the tank.-within the tank settles and condenses predominantly' on .The mentionedobjects and results may be attained the lower or bottom portions of thetank :Iv'ltallS-v F0?I i by depositing suitable materials, including arelatively' example, corrosion-induced leaks in oil tanks fof the 'crosslargeamount ofvPortland cement or the like, into the tank sectionallycurved-bottom types develop onlylin'arelativewhich is to be renovated orprotected against corrosive ly narrow band extending longitudinallyalong the bottom deterioration, the said materials being adapted toproof the tank.. Long experience indicatesthat substantialvide anadhered and stable protective covering over a ly all such leaks developwithin a band' from four to predetermined band of the tank bottom wall,from end ve inches wide because such moisture as may be present 6 to endof the tank, thereby to permanently seal said band within any such tanktends to settle and condense within against the ravages of corrosion,and to expose abody this relatively narrow band of bottom wall. Hence,when of cementitiousmaterial to direct contact with the oil, corrosioncauses such a tank to leak, it may be fairly or other liquid, forabsorbing and consuming moisture assumed that the corrosivedeterioration of the tank walls froml the oil.

will be substantially confined to the mentioned band along 70 In the.case of a tank having corrosion-developed leakt Athe tank bottom andthat other portions of the tank walls holes, the leak-holes may, ifdesired, be enlarged and continue in serviceable condition. Theinvention proplugged from the exterior of the tank prior to depositionwithin the tank of the materials for sealed protective covering of thementioned band of tank bottom wall. Preferably, however, any leak-holesin a tank bottom wall are plugged from within the tank by the materialdeposited in the tank, some of said material being carried into pluggingrelation to any leak-hole by the oil or other liquid initially escapingthrough the leak-hole. The subsequent build-up of the sealing protectivecovering over said band also permanently seals the plugged leak-holewhich, if desired, may be subsequently plugged exteriorly of the tank toprovide a finished exterior appearance.

In the accompanying drawings:

Fig. l is a vertical cross-sectional view through a conventional varietyof home fuel oil storage tank having an adhered protective covering bodyof material covering and sealing a substantial width of the tank bottomwall against deteriorating effects of corrosion;

Fig. 2 is a cross-sectional view on line 2-2 of Fig. l;

Fig. 3 is -a fragmentary cross-sectional view of the lower wall portionof the tank of Figs. 1 and 2, on a larger scale, and prior to depositionin the tank of the sealing and covering material of Figs. l and 2;

Fig. 4 is a view generally similar to Fig. 3 but showing the depositedmaterial settling through the oil, or other liquid, and being carried bythe escaping liquid into plugging relation to a leak-hole in the bottomwall of the tank;

Fig. 5 is a Iview generally similar to Figs. 3 `and 4 but showing thedeposited material covering a substantial width of the bottom wall ofthe tank and also covering the plugged leak-hole therein;

Fig. 6 is a view similar to Fig. 5 but showing the interiorly sealedleak-hole exteriorly plugged by a screw plug; and

Figs. 7-11 are views generally similar to Fig. 3 but showing successivesteps in a modified form of the invention in which a leak-hole may beexteriorly plugged prior to deposition of the sealing and protectivematerial within the tank.

Generally, the following disclosure contemplates applying to an area ofthe inner surface of a metallic, e.g. steel, oil-tank, without removingthe oil therefrom, an aqueous cementitious material whose characteristicingredient is selected, from the class consisting of inorganic siliconcompdnd-iiorgamc calcium compounds. It has been foun a suc a materia wic as greater density than the oil through which it is applied, iscapable of adhering to and solidifying upon the inner surface of thetank, notwithstanding the presence of the oil, in order to provide acoating that seals leaks and prevents corrosion.

Referring to the drawings, a conventional variety of oil storage tank 10is represented in Figs. 1 and 2 partially filled with oil 12. Accordingto the invention a predetermined band or bottom wall, extending from endto end of the tank, is covered by a body of material indicated generallyat 14, which is adhered to the bottom wall as a permanent covering whicheffectively seals the covered area of bottom wall against deterioratingeEects of corrosion.

The bottom wall of the tank 10 may have developed a leak-hole or anumber of leak-holes as a result of corrosion, and Fig. 3 illustrates asmall leak-hole 16 and shows also a region at 18 where the metal hasbeen substantially reduced in thickness by corrosion.

Such a leaky tank, or a deteriorated tank which not yet has reached theleaky stage, or even a new tank, may,

'according to the invention, be renovated for further long water toprovide a owable mixti which, when poured The siliceous cementitiousmaterial may be Portland cemgpt, or the like, and the manantial may beasbstos fibre, preferably, for the most part, relatively coarse andlo'n-g fibres. However, we have found that the fibres lodge in and plugleak-holes more rapidly and eectively if they are coated or partiallycoated with adhering cement which also has a grouping effect on thefibres. The cement adhering to the fibres aids and hastens settling ofthe fibres through oil in the tank, and the grouped fibres can morereadily lodge in and plug relatively large leak-holes, as compared withfibres not coated with the cement.

In what we presently consider to be a preferred procedure, a lime-silicaor lime-clay cement, in an extremely fine dry powder state, isthoroughly pre-mixed with the asbestos fibre to provide a preliminarydry mixture in which the cement powder constitutes from 40% to 60% ofthe mixture. This preliminary dry mixture next may be thoroughly mixedwith siliceous material of the Portland cement variety, in approximatelythe proportions of four arts Portland cement to one part of thepreliminary mixture, wil wam-dm a readilypurble wet mixtureapproximating the consistency of heavy cream.

The fine powdered cement in the preliminary dry mixture xbecomesintimately associated and intermingled with individual fibres and withmatted or interltwined groups of the fibres. During the final mixingwith Portland cement and water, considerable amounts of thewater-activated lime-silica or lime-clay cement adheres to the fibresand groups of fibres. As the ultimate mixture is poured into anoil-containing tank 10, it readily settles through the oil 12. Pouringof the mixture is continued until an accumulation builds up on andspreads over the bottom wall sucient to completely cover thepredetermined band of bottom wall which is to be sealed againstcorrosive deterioration. I'he mixture is of a nature to set tosubstantial hardness while immersed in oil, and the lime-silica orlime-clay cement and the Portland cement cooperate in effecting arelatively strong adhesive bond between the cementitious mass 14 and thetank walls, sealing out all moisture. The water coritent of the pouredmixture becomes absorbed and consumed yby the Portland cement whichsubsequently absorbs such relatively small amounts of moisture as mayget into the tank. The fibre in the set mass minimizes cracking orpulling away from the tank walls due to expansion and contraction of themass and tank. This is especially true when oil 14 in the tank 10constantly covers the cementitious mass 14, a condition which ordinarilyprevails because the cementitious mass may be entirely below the outletfrom the tank.

It is a characteristic of the cementitious mass 14 that, when it hasset, its top surface which is exposed to the oil 12 is at and smooth,presumably due in some measure to the pressure of oil thereon during thesetting process. The smoothness of this top surface, which is subiectedto the eEects of any turbulence of the oil within the tank, minimizesthe likelihood of fragments of the cementitious mass becoming detachedarid floated away in the oil. However, it is recommended that a suitablefilter -be provided in the flow passage between the tank and the oilburner -to ensure against the possibility of particles of the poured mixor of the ultimate protective mass being carried through the oil feedline to the burner,

,` tory & Insulation Corp., of

If there is a leak-hole in the bottom wall of a tank which is beingrenovated, such as the hole 16 shown in Fig. 3, oil will be escapingltherethrough, and some of the poured mixture initially will be carriedwith the oil through the leak-hole until fibres, adhesively grouped orotherwise, lodge and accumulate in the hole and relatively quickly plugthe hole against all but a mere seepage of oil. The subsequentaccumulation of the poured mixture covers the plugged hole 16,preventing any further leakage or seepage of oil through hole 16 afterthe mass 14 has set in sealed attachment to the tank walls. Fig. 4 showsfibres of the poured mixture accumulated in leak-hole 16, and Fig. 5shows the built up cementitious mass 14 covering bottom wall portions ofthe tank and covering the plugged leak-hole 16.

The fibre-plugged leak-hole 16, when desired, may be suitably enlargedexteriorly of the tank for reception of a screw plug, or the like, toprovide a finished exterior appearance. 'Fig 6 shows such an exteriorlyapplied screw plug at 20. Plug 20 ordinarily will be put in place whilethe poured interior mixture continues in a relatively fluid or plasticcondition and the plug becomes locked and sealed by the interior mixturewhen the latter sets. Or, the plug 20 may be screwed into place afterthe interior mixture has set, the fibre re-inforced interior mass,following complete setting thereof, being of a nature to receive thescrew plug 20 without cracking.

herein. A- dry preparation available under "thiiame 11E-@takingpuwutblguialo., Ine.. of 527 Fifth venue, able under the name New York,N.Y., and a dry preparation avail- Stic-tite and put out by Refrac- 120Wall Street, New York,

l N.Y., may be employed to provide our preliminary mixnalysis indicatesthat Insulag .Ny hier ure of asbestos fibre and lime-silica or lime-claycement.

consists of approxifour arts4 lime-silica Stic-tite consists of p- Iately one part asbestos fibre to lime-clay cement, and that H roximatelone art lime-silica or l1 e-cla cement to UL P Y P Milam-Mm..

four arts as'sfbm cement in each prepahratron consists of approximatelyone part lime to four parts silica or clay. These available drypreparations may be mixed together in approximately the proportions ofone part Stic-tite to three parts Insulag to provide a preliminary drymixture contanin alittle less than two parts cement to one part asbestosEbre. In the nsu ag prepzation, thefbres, to a considerable extent, tendto be matted or intertwined, or otherwise joined, into relatively smallgroups of fibres with a relatively large amount of finely powderedcement intimately associated therewith, which makes this preparationgenerally coarser than the Stic-tite preparation wherein the fibres donot become grouped to any notable extent, and wherein there is arelatively smaller amount of the cement powder. These differences in theltwo preparations areA advantageous in the ultimate pourable mixture inthat the grouped fibres more readily become lodged in fairly largeleak-holes and the relatively individually free fibres more effectivelycan enter and lodge with others to plug smaller leak-holes and cracks.

Figs. 7-11 illustrate a modified tank-renovating procedure wherein anyleak-hole in the bottom of a tank may be initially plugged from theexterior of the tank prior to deposition in the tank of the materialsfor protectively covering the predetermined band of tank bottom wall.Assuming that a tank has a small leak-hole as indicated at 16 in Fig. 3,the hole may be drilled to a larger size, as at 30 in Fig. 7, forreception of a relatively soft rubber plug 32 which is shown in Fig. 7ready to be thrust into the enlarged hole 30. Oil gushes out through theenlarged hole until plug 32 is in place, as in Fig. 8, stopping all buta slight seepage past the plug. But the oil quickly acts on the softrubber plug with deteriorating effect and causes substantial swelling ofthe plug which relatively quickly takes the general form as representedin Fig. 9. It is essential that deterioration of the rubber plug bearrested before the plug becomes decomposed to a degree which woulddestroy its effectiveness as a plug, and this may be accomplished bydeposition in the tank of material which spreads over the bottom of thetank, as described in connection with Figs. 1-6, and over the rubberplug as in Fig. 10. The deposited material may be the same mix whichforms the protective body 14 in the Figs. 1-6 embodiment, in which casethe body 14 effectively seals the plugged hole against entrance of anyadditional oil to the rubber, as well as sealing the covered band oftank bottom wall against corrosive deterioration, as described inconnection with Figs. 1-6. Or water glass 34 may be first deposited inthe tank to provide a sealing coating over the plug and over the tankbottom area which is to be protected, followed by deposition of Portlandcement to provide a stabilizing protective body 14' over the water glass34, in Fig. 11.

It should be understood that the invention, in its broader aspects,provides a tank-renovating procedure and method wherein any of a varietyof inorganic siliceous, cementitious materials, having specific gravitygreater than that of an organic liquid stored in a metal tank, may bepoured into the filled or partially filled tank to renovate the tankwhile it continues to be filled or partially filled with oil, or otherliquid. The poured material preferably will be mineral aqueouscementitious material, suitable examples of which are Portland cement,Atlas cement and Keenes cement with water added suflicient to give thecement the consistency of relatively heavy cream.

The pourable material in some cases, such as when a tank has norelatively large leak-holes, may consist entirely of one of thementioned mineral aqueous cementitious materials, rendered pourable andsettable by addition of a suitable amount of water. When fibres areomitted from the pourable material, some cracking of the protective bodymay occur in the setting process, but minor cracks, apparently, do noteffect the effectiveness of the protective mass, presumably because thecement tends to absorb and consume moisture which otherwise mightcondense on the tank walls. Neither do such minor cracks materiallyincrease the likelihood of fragments becoming loosened or broken awayfrom the mass as a result of turbulence of oil in the tank, especiallywhen the oil inlet pipe is equipped with a spray nozzle as indicated at1l in Figs. 1 and 2, such a nozzle 11 being recommended in all cases toavoid concentration of a stream of incoming oil at any one location.Nozzle 11 relatively gently sprays the incoming oil with no substantialcreated turbulence wthin the tank.

Addition of fibre to the cement usually will be found desirable,inasmuch as the fibres initially lodge in leakholes and cracks to effectplugging thereof before the poured material accumulates on the tank wallportions and ultimately sets in adhered covering relation to thementioned predetermined band of bottom wall which becomes permanentlysealed against corrosive deterioration. Also, the fibres strengthen thecementitious mass, minimizing any tendency of the material to crack orpull away from the tank walls. If the fibres are mixed directly with thesliceous cement and water when preparing the pourable mixture, thefibres preferably should be asbestos fibres, or comparable mineralfibres of a nature to settle through oil. On the other hand, if thefibres are pre-mixed with lime-silica or lime-clay cement to provide apreliminary dry mixture as earlier described herein, other varieties offibres may be employed, such as vegetable fibres because the fibres ofthis preliminary mixture become coated or partially coated with thelime-silica or lime-clay cement when the latter is activated by thewater in the ultimate mixture, and the adhering cement causes the fibresto settle through the oil and they can serve the unctions described inconnection with asbestos fibres.

It is intended that the patent shall cover, by suitable expression inthe appended claims, whatever features of patentable novelty exist inthe invention disclosed.

We claim as our invention:

1. The method of coating an inner bottom surface area of the walls of agenerally cylindrical horizontally disposed oil-containing tank,comprising the steps of predetermining a relatively narrow band ofbottom wall of the tank within which band substantially all corrosivedeterioration of the tank occurs, depositing through a top opening inthe tank an aqueous cementitious material in quantity to cover saidpredetermined band by settling through the oil in the tank, saiddeposited material containing a mixture of lime-clay gguulnandag and towhich has lle en added inaqueous vmixture a compound from the classconsisting of compounds fpfsiliand calcium; the said deposited materialbeing of a nature to smc through the oil in the tank into protectivecovering relation to said predetermined band of tank bottom wall, andletting all of the band-covering deposited material set to substantialrigidity while immersed in said oil.

2. The method of renovating an oil tank which has developed leak holesas a result of corrosive deterioration comprising predetermining arelatively narrow horizontally extending critical band of tank wallwherein substantially all said corrosive deterioration of the tank willoccur, preparing an aqueous mixture of a fibrous material and acementitious material having greater density than the oil in the tank,settling said mixture through the oil whereby said fibrous material oatsto and lodges in and substantially to plug the leak-holes, continuingthe settling of the material until a substantial accumulation thereofcovers only slightly more than said predetermined critical band and saidleak-holes, and letting all of the band covering accumulation set in thepresence of said oil to provide a stable, substantially rigid coveringover said critical band and said leak-holes.

3. The method of renovating a generally cylindrical horizontallydisposed oil-containing storage tank susceptible of corrosivedeterioration producing leak-holes in a lower wall portion thereof,comprising predetermining that relatively narrow longitudinallyextending band of tank wall wherein substantially all said corrosivedeterioration will occur, providing a pourable aqueous mixture of amineral cement and a lime-silica compound interspersed with fibrousmaterial and having specific gravity greater than that of the oil in thetank, pouring said mixture into the tank thereby causing the mixture tosettle through the oil and accumulate on said lower wall portions of thetank, a relatively small amount of said poured mixture being initiallycarried through said leak-holes by escaping oil until fibres in themixture lodge in and effectively plug the leak-holes, continuing thepouring until said accumulation builds up on and spreads over onlyslightly more than the total area of said predetermined band of tankwall including said fibreplugged leak-holes, said poured mixture beingof a nature to relatively strongly adhere to the covered wall portionsof the tank and to set into a relatively rigid brereinforcedcementitious body protectively sealing said covered band of wall againstcorrosive deterioration.

4. The method of renovating an oil-containing storage tank as defined inclaim 3 wherein the said fibres are pre-mixed with finely powderedlime-silica cement in a dry state to provide a dry preliminary mixturein which the powdered cement constitutes from 40% to 60% of the drymixture, the said pourable aqueous mixture consisting of approximatelyone part of the said preliminary dry mixture and four parts of the saidmineral cement.

5. The method of renovating a generally cylindrical horizontallydisposed oil-containing storage tank having a leak-hole in a lower wallportion thereof, comprising predetermining a relatively narrowhorizontally extending band of tank wall wherein substantially allcorrosive deterioration of the tank will occur, pre-mixing finelypowdered lime-clay cement in a dry state with fibres to provide a drypreliminary mixture in which the powdered cement constitutes from 40% to60% of the dry mixture, whereby the cement powder becomes intimatelyassociated and intermingled with the fibres, followed by thoroughlymixing approximately one part of the said preliminary mixture withapproximately four parts of settable siliceous cement, and watersuicient to provide a pourable mixture having substantially theconsistency of heavy cream, and then pouring the latter said mixtureinto the tank through a top wall opening whereby the poured mixturesettles through the oil and accumulates on lower wall portions of thetank, some of the settled mixture being carried by leaking oil into andthrough the said leak-hole until fibres in the mixture lodge in andsubstantially plug the leak-hole, the said intimacy of association ofthe cement and fibres in said preliminary mixture resulting insubstantial amounts of the pre-mix cement becoming intimately adhered tothe libres when the cement is activated by said water, whereby settlingof the fibres s aided by the adhering cement which also tends to unitefibres in relatively small groups which facilitate the said lodging oflibres in the leak-hole, the pouring of the mixture into the tank beingcontinued until the accumulation thereof has built up on and spread overonly slightly more than the total area of said predetermined bandincluding the portion thereof in which said leak-hole is located, andall of the said accumulation being allowed to set within the oil tosubstantial rigidity in adhering sealed relation to the said band oftank wall bottom wall portions of the tank.

References Cited in the file of this patent UNITED STATES PATENTS1,281,690 Stern Oct. 15, 1918 2,110,053 Phillips Mar. 1, 1938 2,235,937Linberg Mar. 25, 1941 2,320,633 Mitchell et al June 1, 1943 2,328,292Painter Aug. 31, 1943 2,502,409 Bour Apr. 4, 1950 2,526,674 Larsen Oct.24, 1950 2,629,667 Kaveler Feb. 24, 1953 2,795,507 Kaveler June 11, 19572,874,778 Kaveler Feb. 24, 1959 OTHER REFERENCES Volclay Bentonite, Data#230-3; Data 231-D; page 2; Data #202, pages l and 2.

1. THE METHOD OF COATING AN INNER BOTTOM SURFACE AREA OF THE WALLS OF AGENERALLY CYLINDRICAL HORIZONTALLY DISPOSED OIL-CONTAINING TANK,COMPRISING THE STEPS OF PREDETERMINING A RELATIVELY NARROW BAND OFBOTTOM WALL OF THE TANK WITHIN WHICH BAND SUBSTANTIALLY ALL CORROSIVEDETERIORATION OF THE TANK OCCURS, DEPOSITING THROUGH A TOP OPENING INTHE TANK AN AQUEOUS CEMENTITIOUS MATERIAL IN QUANTITY TO COVER SAIDPREDETERMINED BAND BY SETTLING THROUGH THE OIL IN THE TANK, SAIDDEPOSITED MATERIAL CONTAINING A MIXTURE OF LIME-CLAY CEMENT AND FIBRESAND TO WHICH HAS BEEN ADDED IN AQUEOUS MIXTURE A COMPOUND FROM THE CLASSCONSISTING OF COMPOUNDS OF SILICON AND CALCIUM, THE SAID DEPOSITEDMATERIAL BEING OF A NATURE TO SETTLE THROUGH THE OIL IN THE TANK INTOPROTECTIVE COVERING RELATION TO SAID PREDETERMINED BAND OF TANK BOTTOMWALL, AND LETTING ALL OF THE BAND-COVERING DEPOSITED MATERIAL SET TOSUBSTANTIAL RIGIDITY WHILE IMMERSED IN SAID OIL.